Frequently asked questions

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What is the ‘Allsteel tank head forming system’?
The Allsteel tank head forming system consists of a servo-controlled hydraulic press, compressed air system, and appropriate tooling to form various tank heads.
How does the Allsteel Tank Head Forming system really work?
The system is simple in principle: an appropriate blank of sheet metal is placed into the press. Then the ram with the upper tool descends and grips the blank around the desired perimeter. Once the blank is gripped sufficiently to eliminate slipping, compressed air is admitted under the blank and the dish is formed by air pressure. A laser sensor monitors the dish depth, and once the desired depth is reached the air is dumped and the ram returns to top position. The dished part is now ready to remove from the press.
How does the Allsteel system compare to conventional methods of forming tank heads?
Firstly, the Allsteel system is orders of magnitude more productive than conventional forming methods such as multi-hit forming or spinning (for circular heads only). Instead of hours spent making a part, the Allsteel system cycle times range from approx. two to four minutes. Secondly, since there is no mechanical contact with the inside of the dish during forming, no time-consuming secondary sanding or polishing operations are needed. Polished materials retain their polish.
What shapes of tank heads can the Allsteel system produce?
Any shape if it has reasonably rounded corners: circular, oval, ovoid or tank truck shapes are all possible assuming appropriate dies are used.
What are the maximum sizes and material thicknesses these systems can form?
The maximum size depends on the press bed size… which must clearly be able to accommodate the required tooling and blank sizes. Larger sizes imply more tonnage required to form the part, as does increasing material thickness and yield strength. For example, a 1,000 Ton press can easily form an 8-foot (2.5 meter) diameter aluminum part 0.125” (3 mm) thick; a 3,500 Ton press can form a 12-foot (3.5 meter) diameter stainless steel part 0.2” (5 mm) thick. ALLSTEEL offers larger 4,500T presses, and ‘double-bed’ presses to form up to 16’ diameter heads.
What are the smallest parts these machines can form?
It may at first seem counter-intuitive, but smaller diameter parts, while needing less tonnage, need higher air pressures to form. This can be understood by the fact that if the diameter is halved, the area of the blank reduces by a factor of four (area increases as the square of the diameter). Thus a small part requires more air pressure to form, as the air has less area to act on. For example, the twelve foot diameter 0.2” thick stainless part will need air pressure of approximately 150 Psi (10 Bar) thus reservoir pressure needs to be about 200 Psi (15 Bar) to assure sufficient flow into the dish. A similar part four feet (1.2 Meters) in diameter will need dish air pressure of 450 Psi (30 Bar) to form; reservoir pressure will need to be near 600 Psi (40 Bar) and this is near the maximum air pressure the systems use. For higher forming pressure, hydroforming becomes the preferred method; using liquid instead of air to dish the parts.
What maintenance do these machines require?
Very little; the hydraulic system needs filter replacement regularly, as does the air compressor. The compressor oil needs to be changed less frequently, and the press hydraulic oil even less frequently than that. Maintenance of the coolant system will depend on the type of cooling system used.
What kind of warranty is offered?
Allsteel Tank Head forming systems come with a one-year warranty. Any parts that prove defective within one year will be replaced or repaired. Longer term service contracts are also available; the Allsteel press is equipped with Internet connectivity allowing remote diagnostics and software updates.
Do these machines comply with various international standards?
Yes; the standards complied with will depend on the location of the press.